The eye is a complex sensory organ that allows us to see the world around us. The eye works by gathering light from the environment and converting it into electrical signals that can be interpreted by the brain. The basic structure of the eye includes the cornea, iris, pupil, lens, retina, and optic nerve. The cornea is the transparent outer layer of the eye that helps to focus incoming light. The iris is the colored part of the eye that regulates the amount of light that enters the eye through the pupil, which is the black circular opening in the center of the iris. The lens is a clear, flexible structure located behind the iris that helps to focus light onto the retina. The retina is a thin layer of tissue that lines the back of the eye and contains photoreceptor cells called rods and cones. These cells convert light into electrical signals that are sent to the brain via the optic nerve. The rods are responsible for the low light vision and detecting motion, while the cones are resp
Term Pteridophyta was proposed by Hackel. The study of pteridophytes is known as pteridology. Pteridophytes are known as reptiles of the plant kingdom. They are also called as vascular cryptogams. They are vascular plants, i.e. xylem and phloem are present in it. In pteridophytes, vessels in xylem and companion cells in phloem are absent. Pteridophytes are used for medicinal purposes and as soil binders. They are also frequently grown as ornamentals. Pteridophytes are more adapted terrestrial plants as compared to bryophytes. Because vascular tissue is present in them and they have roots. Pteridophytes are not completely successful terrestrial plants because they need water for fertilization, so pteridophytes grow in cool, shady and moist places. In pteridophytes, the plant body is completely differentiated into root, stem and leaves. The primary root of pteridophytes remains alive for a short period. After some time it is replaced by adventitious roots. The stem is erect or prostrate